U.S. patent application number 10/338542 was filed with the patent office on 2003-09-25 for methods and apparatus for optical communication.
Invention is credited to Zhou, Ping.
Application Number | 20030179985 10/338542 |
Document ID | / |
Family ID | 32710977 |
Filed Date | 2003-09-25 |
United States Patent
Application |
20030179985 |
Kind Code |
A1 |
Zhou, Ping |
September 25, 2003 |
Methods and apparatus for optical communication
Abstract
A method and apparatus for communications according to various
aspects of the present invention comprises a switching system
configured to receive optical signals and direct the optical
signals along a selected optical path. The switching system
suitably includes more than one switch, and at least one of the
switches may include a variable refractive material having a first
state and a second state, wherein the optical signal is transmitted
via a first path when the variable refractive material is in the
first state and the individual channel signal is transmitted via a
second path when the variable refractive material is in the second
state. The switching system may alternatively or additionally
include a switch element having a reflective state and a
transmissive state, wherein the optical signal is reflected via a
first path when the switch element is in the reflective state and
the individual channel signal is transmitted via a second path when
the switch element is in the transmissive state.
Inventors: |
Zhou, Ping; (Westlake
Village, CA) |
Correspondence
Address: |
Law Offices of Daniel J. Noblitt, LLC
Suite 123
3370 North Hayden Road
Box 258
Scottsdale
AZ
85251
US
|
Family ID: |
32710977 |
Appl. No.: |
10/338542 |
Filed: |
January 7, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60346662 |
Jan 8, 2002 |
|
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Current U.S.
Class: |
385/16 ; 385/17;
385/24 |
Current CPC
Class: |
G02B 6/3538 20130101;
H04Q 2011/0035 20130101; G02B 6/29395 20130101; G02F 1/31 20130101;
G02B 6/3568 20130101; G02B 6/3524 20130101; G02B 6/3572 20130101;
G02B 6/29373 20130101; G02B 6/351 20130101; G02B 6/3576 20130101;
G02B 6/3556 20130101; H04Q 11/0005 20130101; G02B 6/3528 20130101;
G02B 6/3544 20130101; G02B 6/3546 20130101; G02B 6/356
20130101 |
Class at
Publication: |
385/16 ; 385/17;
385/24 |
International
Class: |
G02B 006/35; G02B
006/28 |
Claims
1. An optical switch for selectively transmitting light from a
light source to a light target, including: at least one input
configured to receive the light from the light source; at least one
output configured to provide light to the light target; and a
switch configured to selectively transmit light from the input to
the output via a selected optical path, wherein the switch includes
at least one of: a variable refractive material having at least a
first state and a second state, wherein light is transmitted via a
first path when the variable refractive material is in the first
state and light is transmitted via a second path when the variable
refractive material is in the second state; and a switch element
having a reflective state and a transmissive state, wherein light
is reflected via a first path when the switch element is in the
reflective state and light is transmitted via a second path when
the switch element is in the transmissive state.
2. An optical switch according to claim 1, wherein only light
within a selected wavelength range is substantially reflected via
the first path when the switch element is in the reflective state
and light within the selected wavelength range is substantially
transmitted via the second path when the switch element is in the
transmissive state.
3. An optical switch according to claim 1, wherein the switch
element has a filter state, wherein light of a first wavelength is
reflected via the first path and light of a second wavelength is
transmitted via the second path when the switch element is in the
filter state.
4. An optical switch according to claim 1, wherein the variable
refractive material changes from the first state to the second
state in response to a change in at least one of an electric field,
a magnetic field, a control light, and a temperature applied to the
variable refractive material.
5. An optical switch according to claim 1, wherein the switch
element changes between the transmissive state and the reflective
state in response to a change in at least one of an electric field,
a magnetic field, a control light, and a temperature applied to the
switch element.
6. An optical switch according to claim 1, wherein the selected
optical path is a three-dimensional path.
7. An optical switch according to claim 1, wherein the switch
includes: the first variable refractive material having the first
state and the second state, wherein light is transmitted via the
first path when the first variable refractive material is in the
first state and light is transmitted via the second path when the
first variable refractive material is in the second state; and a
second variable refractive material configured to receive light
from the first variable refractive material only when the first
variable refractive material is in the first state, and wherein the
second variable material has a first state and a second state,
wherein light is transmitted via a third path when the second
variable refractive material is in the first state and light is
transmitted via a fourth path when the second variable refractive
material is in the second state.
8. An optical switch according to claim 1, wherein the switch is
configured to receive light from two light sources and direct light
to one light target, wherein the light is directed from the first
light source to the light target when the switch is in the first
state and light from the second light source is directed to the
light target when the switch is in the second state.
9. An optical switch according to claim 8, wherein at least part of
the light from the switch is provided as a feedback signal to a
feedback system.
10. An optical switch according to claim 1, wherein the switch
element includes a reflective portion and a transmissive portion,
and wherein the reflective portion is moved into the path of the
light when the switch element is in the reflective state and the
transmissive portion is moved into the path of the light when the
switch element is in the transmissive state.
11. An optical switch according to claim 1, wherein the switch
element includes a latch mechanism to maintain a selected state of
the switch element.
12. An optical switch according to claim 11, wherein the latch
mechanism includes: at least one notch defined in the switch
element; and a retainer configured to lodge within the notch when
the switch element is in the selected state.
13. An optical switch according to claim 1, wherein the switch
element may be switched between the reflective state and the
transmissive state by one signal.
14. An optical switch according to claim 1, wherein the reflective
state and the transmissive state are wavelength dependent.
15. An optical switch according to claim 1, wherein the switch
element includes a material that changes between the reflective
state and the transmissive state in response to an event without
moving.
16. An optical switch according to claim 1, wherein the switch
comprises at least one of optical media, optical cavities, cells,
windows, waveguides, fibers, lenses, filters, coatings, optical
interfaces, optical resonance cavities, and mirrors.
17. An optical switch according to claim 1, wherein the switch
changes state in response to a change in a control light.
18. An optical switch according to claim 1, further including at
least one lens configured to change the optical path of the
light.
19. An optical switch according to claim 18, wherein the lens
includes a concave lens.
20. An optical switch according to claim 18, wherein the lens is
configured to enlarge the angle change of the optical path.
21. An optical switch according to claim 1, wherein the variable
refractive material comprises at least one of a solid medium, a
plastic medium, a liquid medium, a liquid crystal, or a gaseous
medium.
22. An optical switch according to claim 1, further including a
second switch in the selected optical path.
23. An optical switch according to claim 1, wherein the optical
path is adjustable with respect to the light target to adjust the
optical signal level.
24. An optical switch according to claim 1, wherein the switch is
configured to transmit packet signals according to information in
the packet signals.
25. An optical switch according to claim 24, further including a
control system configured to receive the information in the packet
signals and control the state of the switch according to the
information.
26. An optical switch according to claim 25, further including an
optical delay system between the light source and the switch.
27. A communications system, including: a demultiplexer configured
to receive multiple channels of optical signals via one connection
and separate each channel into an individual channel signal; a
switching system configured to receive each individual channel
signal from the demultiplexer and direct the individual channel
signal along a selected optical path, wherein the switching system
includes more than one switch, and wherein at least one of the
switches includes at least one of: a variable refractive material
having at least a first state and a second state, wherein the
individual channel signal is transmitted via a first path when the
variable refractive material is in the first state and the
individual channel signal is transmitted via a second path when the
variable refractive material is in the second state; and a switch
element having a reflective state and a transmissive state, wherein
the individual channel signal is substantially reflected via a
first path when the switch element is in the reflective state and
the individual channel signal is substantially transmitted via a
second path when the switch element is in the transmissive state;
and a control system configured to control the switching
system.
28. A communications system according to claim 27, wherein only an
individual channel within a selected wavelength range is
substantially reflected via the first path when the switch element
is in the reflective state and the individual channel within the
selected wavelength range is substantially transmitted via the
second path when the switch element is in the transmissive
state.
29. A communications system according to claim 27, wherein the
switch element has a filter state, wherein a first channel signal
of a first wavelength is substantially reflected via the first path
and a second channel signal of a second wavelength is substantially
transmitted via the second path when the switch element is in the
filter state.
30. A communications system according to claim 27, wherein the
variable refractive material changes from the first state to the
second state in response to a change in at least one of an electric
field, a magnetic field, a control light, and a temperature applied
to the variable refractive material.
31. A communications system according to claim 27, wherein the
switch element changes between the transmissive state and the
reflective state in response to a change in at least one of an
electric field, a magnetic field, a control light, and a
temperature applied to the switch element.
32. A communications system according to claim 27, wherein the
selected optical path is a three-dimensional path.
33. A communications system according to claim 27, wherein the
switch includes: the first variable refractive material having the
first state and the second state, wherein light is transmitted via
the first path when the first variable refractive material is in
the first state and light is transmitted via the second path when
the first variable refractive material is in the second state; and
a second variable refractive material configured to receive light
from the first variable refractive material only when the first
variable refractive material is in the first state, and wherein the
second variable material has a first state and a second state,
wherein light is transmitted via a third path when the second
variable refractive material is in the first state and light is
transmitted via a fourth path when the second variable refractive
material is in the second state.
34. A communications system according to claim 27, wherein at least
one of the switches is configured to receive two individual channel
signals and direct the channel signals along a single selected
path, wherein the first channel signal is directed along the
optical path when the switch is in the first state and the second
channel signal is directed along the optical path when the switch
is in the second state.
35. A communications system according to claim 34, wherein at least
part of the channel signal directed along the optical path is
provided as a feedback signal to a feedback system.
36. A communications system according to claim 27, wherein the
switch element includes a reflective portion and a transmissive
portion, and wherein the reflective portion is moved into the path
of the light when the switch element is in the reflective state and
the transmissive portion is moved into the path of the light when
the switch element is in the transmissive state.
37. A communications system according to claim 27, wherein the
switch element includes a latch mechanism to maintain a selected
state of the switch element.
38. A communications system according to claim 37, wherein the
latch mechanism includes: at least one notch defined in the switch
element; and a retainer configured to lodge within the notch when
the switch element is in the selected state.
39. A communications system according to claim 27, wherein the
switch element may be switched between the reflective state and the
transmissive state by one signal.
40. A communications system according to claim 27, wherein the
reflective state and the transmissive state are wavelength
dependent.
41. A communications system according to claim 27, wherein the
optical path is adjustable with respect to a light target to adjust
the optical signal level.
42. A communications system according to claim 27, wherein at least
one of the switches comprises at least one of optical media,
optical cavities, cells, windows, waveguides, fibers, lenses,
filters, coatings, optical interfaces, optical resonance cavities,
and mirrors.
43. A communications system according to claim 27, wherein the
switch element includes a material that changes between the
reflective state and the transmissive state in response to an event
without moving.
44. A communications system according to claim 27, wherein the
switch changes state in response to a change in a control
light.
45. A communications system according to claim 27, wherein the
variable refractive material comprises at least one of a solid
medium, a plastic medium, a liquid medium, a liquid crystal, or a
gaseous medium.
46. A communications system according to claim 27, further
including at least one lens configured to change the optical path
of the light.
47. A communications system according to claim 46, wherein the lens
includes a concave lens.
48. A communications system according to claim 46, wherein the lens
is configured to enlarge the angle change of the optical path.
49. A communications system according to claim 27, further
including a second switch in the selected optical path.
50. A communications system according to claim 27, wherein the
switch is configured to transmit packet signals according to
information in the packet signals.
51. A communications system according to claim 50, further
including a switch control system configured to receive the
information in the packet signals and control the state of the
switch according to the information in the packet signals.
52. A communications system according to claim 51, further
including an optical delay system between the light source and the
switching system.
53. A communications system according to claim 27, further
including a monitoring system configured to monitor signals from
the switching system and provide information to the control system
relating to the quality of the monitored signals.
54. A communications system according to claim 27, further
including a signal adjustment system configured to adjust the
quality of the signals provided by the switching system.
55. A communications system according to claim 54, wherein the
signal adjustment system is configured to adjust a refractive index
of the variable refractive material.
56. A method of transmitting an optical signal from a light source
to a light target, including: identifying a selected optical path
for the optical signal; directing the optical signal via the
selected optical path, wherein directing the optical signal
includes at least one of: changing a refractive state of a switch
from a first state to a second state, wherein a first path is
selected when the switch is in the first state and a second path is
selected when the switch is in the second state; and changing a
state of a switch element having a reflective state and a
transmissive state, wherein a first path is selected when the
switch element is in the reflective state and a second path is
selected when the switch element is in the transmissive state.
57. A method of transmitting an optical signal according to claim
56, wherein the optical path of only an optical signal within a
selected wavelength range is selected according to the state of the
switch element.
58. A method of transmitting an optical signal according to claim
56, wherein changing the refractive state of the switch includes
changing at least one of an electric field, a magnetic field, a
control light, and a temperature applied to the variable refractive
material.
59. A method of transmitting an optical signal according to claim
56, wherein changing the state of the switch element having the
reflective state and the transmissive state includes changing at
least one of an electric field, a magnetic field, a control light,
and a temperature applied to the switch element.
60. A method of transmitting an optical signal according to claim
56, wherein the selected optical path is a three-dimensional
path.
61. A method of transmitting an optical signal according to claim
56, further including changing a second switch from a first state
to a second state, wherein the second switch is configured to
receive the optical signal from the first switch only when the
second switch is in the selected optical path, and wherein the
second switch has a first state and a second state, wherein the
optical signal is transmitted via a third path when the second
switch is in the first state and the optical signal is transmitted
via a fourth path when the second switch is in the second
state.
62. A method of transmitting an optical signal according to claim
56, wherein the switch element includes a reflective portion and a
transmissive portion, and wherein changing the state of the switch
element includes moving the reflective portion into the path of the
optical signal when the switch element is in the reflective state
and moving the transmissive portion into the path of the optical
signal when the switch element is in the transmissive state.
63. A method of transmitting an optical signal according to claim
56, wherein the switch element includes a material that changes
between the reflective state and the transmissive state in response
to an event without moving.
64. A method of transmitting an optical signal according to claim
56, wherein directing the optical signal includes changing a
control light along a control path that is parallel to at least a
part of the selected optical path.
65. A method of transmitting an optical signal according to claim
56, wherein the optical signals include packet signals.
66. A method of transmitting an optical signal according to claim
65, further including: reading information in the packet signals;
and directing the optical signal according to the information in
the packet signals.
67. An optical packet cross-switching system, comprising: at least
one optical wavelength de-multiplexing (DeMUX) module; at least one
optical wavelength multiplexing (MUX) module; at least one optical
packet switching system; at least one optical across switch; at
least one Multi-channel monitoring (MCM) system; at least one
multi-channel optical variable attenuation (MCOVA) system which is
a built-in function of the optical switching modules; at least one
optical ADD module which contains at least one wavelength tunable
transmitters and/or electrical signal to optical signal converter;
at least one optical Drop module with wavelength combiner and/or
optical signal to electrical signal converter; at least one central
control system; at least one communication port links to the
network management system; and the software to run the whole
system.
68. An optical packet cross-switching system according to claim 67,
wherein the system is connected as the following sequence: the
optical wavelength de-multiplexing (DeMUX) modules are connected to
optical packet switches; optical ADD modules are connected to the
optical packet switches; the optical packet switches are connected
to optical cross switches; the optical cross switches are connected
to the optical Drop modules and optical wavelength multiplexing
(MUX) modules; and the central control unit is connected with the
network management system and each subsystem list above.
69. An optical packet cross-switching system according to claim 67,
wherein each element includes a distributed control unit, and
wherein each distributed control unit is connected to the central
control unit.
70. An optical packet cross-switching system according to claim 67,
wherein the central control unit of the optical packet cross
switching system can communicate with a network management system
through the packet switching unit as an option.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/346,662, filed Jan. 8, 2002, and
incorporates the disclosure of the application by reference.
FIELD OF THE INVENTION
[0002] The invention relates to methods and apparatus for optical
switches and optical communication.
BACKGROUND OF THE INVENTION
[0003] Optical switches are widely used in the fiber optical
communication industry. Typically, optical switches operate as
network protection switches or elements of optical add/drop
systems. As transmission bands, switching speeds, and traffic
capacities increase, communication systems demand smaller, cheaper,
and better devices and switches.
[0004] Conventional optical switches used for network protection
are mostly mechanical switches, which contribute significant bulk
due to the design configuration. Conventional switches normally
employ a rotation mirror or rotation slice inside the optical path
to steer the beam in different directions to perform the switching
function. Due to the large size and rotation of the mirror, the
switch normally requires a collimator for each optical port (input
and output) to extend the optical path to put rotation mirrors and
other switching mechanics into the optical path to block or switch
the optical beams. The cost to build each individual switch module
is difficult to reduce due to the many components employed, such as
the collimators.
[0005] Optical communication systems also generally employ other
components, such as optical add/drop multiplexers (OADM). These
systems require compact switches, ideally integrated into a small
switch array. Conventional switches, however, are typically
produced using MEMS technology, which is very expensive. Further,
MEMS switches are difficult to equip with a latching mechanism to
maintain the status of the switch when power is terminated. In
addition, MEMS switches typically have moving parts subject to wear
and often require high voltage to control the switch, both of which
tend to reduce reliability.
SUMMARY OF THE INVENTION
[0006] A method and apparatus for communications according to
various aspects of the present invention comprises a switching
system configured to receive optical signals and direct the optical
signals along a selected optical path. The switching system
suitably includes more than one switch, and at least one of the
switches may include a variable refractive material having a first
state and a second state, wherein the optical signal is transmitted
via a first path when the variable refractive material is in the
first state and the individual channel signal is transmitted via a
second path when the variable refractive material is in the second
state. The switching system may alternatively or additionally
include a switch element having a reflective state and a
transmissive state, wherein the optical signal is reflected via a
first path when the switch element is in the reflective state and
the individual channel signal is transmitted via a second path when
the switch element is in the transmissive state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A more complete understanding of the present invention may
be derived by referring to the detailed description when considered
in connection with the following illustrative figures. In the
following figures, like reference numbers refer to similar elements
and steps.
[0008] FIG. 1 is a block diagram of a switching system according to
various aspects of the present invention;
[0009] FIG. 2 is an illustration of a 1.times.2 optical switch
having a variable refractive material;
[0010] FIG. 3 is an illustration of a variable refractive material
having adjacent media with different refractive indices;
[0011] FIG. 4 is an illustration of a 2.times.1 optical switch
having a variable refractive material;
[0012] FIG. 5 is an illustration of a 2.times.2 optical switch
having a variable refractive material;
[0013] FIG. 6 is an illustration of an optical switch having a
variable refractive material and a three-dimensional optical
path;
[0014] FIG. 7 is an illustration of a three-dimensional optical
switch array;
[0015] FIGS. 8A-F are diagrams of optical media having different
orientations and/or optical paths;
[0016] FIGS. 9A-C are diagrams of optical systems having lenses,
switches, and mirrors to change the optical path;
[0017] FIG. 10 an illustration of a 1.times.2 optical switch having
a variable refractive material responsive to electrical
signals;
[0018] FIGS. 11A-B are illustrations of variable refractive
materials responsive to electric and/or magnetic fields;
[0019] FIGS. 12A-C are illustrations of variable refractive
materials responsive to light;
[0020] FIG. 13 is an illustration of a switch array having
electrically controllable optical switches;
[0021] FIG. 14 is an illustration of an optical switch responsive
to heat;
[0022] FIG. 15 an illustration of an optical switch responsive
using a liquid crystal material;
[0023] FIG. 16 an illustration of an optical switch responsive to
light;
[0024] FIG. 17 an illustration of an optical switch employing
waveguides;
[0025] FIG. 18 is an illustration of a switch array having multiple
switching elements;
[0026] FIGS. 19A-C are illustrations of a mechanical switch;
[0027] FIG. 20 is an illustration of an optical switch using a
mechanical switch;
[0028] FIG. 21 is an illustration of a mechanical switch having a
latching mechanism;
[0029] FIG. 22 is an illustration of a switching array having
multiple mechanical switches;
[0030] FIG. 23 is a diagram of a communications system using a
switching array;
[0031] FIG. 24 is a diagram of a 2.times.1 switch coupled to a
signal detector;
[0032] FIGS. 25A-B are diagrams of optical packet switches; and
[0033] FIG. 26 a diagram of a communications system using a
switching array and configured for optical packets.
[0034] Elements and steps in the figures are illustrated for
simplicity and clarity and have not necessarily been rendered
according to any particular sequence. For example, steps that may
be performed concurrently or in different order are illustrated in
the figures to help to improve understanding of embodiments of the
present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0035] The present invention is described partly in terms of
functional components and various processing steps. Such functional
components may be realized by any number of components configured
to perform the specified functions and achieve the various results.
For example, the present invention may employ various elements,
lenses, refractors, collimators, materials, light sources, light
transmitters, reflectors, and the like, which may carry out a
variety of functions. In addition, the present invention may be
practiced in conjunction with any number of applications,
environments, communications systems, and actuating
characteristics, and the systems described are merely exemplary
applications for the invention. Further, the present invention may
employ any number of conventional techniques for manufacturing,
assembling, integration, and the like.
[0036] Referring now to FIG. 1, an optical switching module 100
according to various aspects of the present invention may be
implemented in conjunction with a light source 110, a light target
112, a switch 114, and an actuator 116. The light source 110 is
configured to provide light for selective transmission by the
switch 114. The light source 110 may comprise any appropriate
system for providing light to the switch 114, such as a
conventional fiber optic strand or waveguide coupled to the switch
114. Further, the light source 110 may include additional
components for directing or enhancing the light, such as focusing,
collimating, amplifying, deflecting, and/or filtering the light.
The light may be generated by and/or received from any appropriate
light generator, such as a laser.
[0037] Conversely, the light target 112 selectively receives the
light from the light source 110 via the switch 114. The light
target 112 may comprise any appropriate receiving element for the
light, such as an output fiber, output waveguide, or signal
detector. The light target 112 may also comprise any appropriate
element for registering or amplifying the light received, such as
an optical amplifier, a charge coupled device, a photocell, a
photodiode, or other optical signal detection system. Further, the
light target 112 may include additional components for receiving,
directing, or enhancing the light, such as focusing, collimating,
amplifying, deflecting, and/or filtering the light.
[0038] The switch 114 selectively changes the path of incident
light. More particularly, the switch 114 has at least two states.
The state of the switch is responsive to at least one trigger
event, such as a trigger event caused by the actuator 116. The path
of the incident light is directed to different light targets 112
according to the state of the switch 114. The path of the light may
be changed in any suitable manner, such as by reflectively and/or
refractively changing the path of the light.
[0039] The actuator 116 selectively changes the state of the switch
114. The configuration of the actuator 116 may be adapted according
to the responsiveness and/or other characteristics of the switch
114. Any appropriate actuator may be used to change the state of
the switch 114, including a mechanical actuator, an electrical
actuator such as a pair of electrodes, a heating element, a light
source, a magnetic field generator, a chemical, or any other system
for changing the state of the particular switch 114. For example,
the actuator 116 may be configured to change the state of the
switch 114 between a transmissive state and a reflective state.
Alternatively, the actuator 116 may be configured to change the
state of the switch between a first state having a first refractive
index and a second state having a second refractive index to change
the path of light passing through the switch. In another
embodiment, the actuator 116 may, alternatively or additionally,
change the state of the switch 114 from a first state having a
first reflective path to a second state having a second reflective
path. The actuator 116 may interact with the switch 114
electrically or via any other suitable mechanism or characteristic,
such as magnetically, optically, thermally, and/or nonlinearly. In
various embodiments, the switch 114 and actuator 116 may be
configured with or without moving parts.
[0040] Referring to FIG. 2, an exemplary embodiment of the optical
switching module 100 according to various aspects of the present
invention comprises a 1.times.2 optical switching module 200. The
1.times.2 optical switching module 200 includes the light source
110 comprising an input port 210 and the light target 112
comprising two output ports 212A-B. The input port 210 and output
ports 212A-B suitably comprise fiber optic strands. The input port
210 and output ports 212A-B may include additional components to
improve the optical characteristics of the input port 210 and
output ports 212A-B, such as collimators 214A-B, 216.
[0041] In the present embodiment, the switch 114 comprises a fully
optical, mirrorless optical switch including one or more media
having an adjustable refractive index. In the present embodiment,
the switch 114 comprises three media 220, 222, 224 having
refractive indices of n1, n2, and n3, respectively. At least one of
the refractive indices, such as the second refractive index n2, is
variable. In an alternative embodiment, the switch comprises only
two media 220, 222, such that n1 and n3 are substantially
identical. Any appropriate number of media, however, having any
suitable regfractive indices may be deployed.
[0042] When the refractive index n2 is adjusted to have a first
value, incident light is directed to the first output port 212A.
Conversely, when the refractive index n2 is adjusted to have a
second value, incident light is directed to the second output port
212A. Thus, by changing the refractive index of one or more optical
media, the light from the light source 110 may be selectively
directed to the light target 112.
[0043] The various optical media 220, 222, 224 may comprise any
suitable materials, including crystal, glass, solution,
semiconductor material, nonlinear optical material, liquid
materials such as liquid crystal and other liquid organic and
inorganic material, plastic materials such as polymers or other
organic material, gaseous materials, and other organic and
inorganic material and/or compounds. For example, the variable
medium 222 having the variable refractive material n2 may comprise
a liquid or gas optical medium contained within a cavity. The
cavity may be formed within a solid material comprising the other
optical media, or may be formed by a container, such as a container
of glass, semiconductor, crystal, plastic, or other suitable
material.
[0044] In addition, the various media may be configured in any
suitable manner. The switch 114 of the present embodiment comprises
at least two optical interfaces 226, 228 where two different media
meet, such as the n1/n2 boundary and the n2/n3 boundary.
[0045] The optical interfaces 226, 228 are configured at an angle
to each other such that incident light is refracted at one or more
of the optical interfaces 226, 228. The angle may be greater than
zero but may be less than the relevant total internal reflection
angle.
[0046] The optical interfaces 226, 228 may be configured in any
appropriate manner to facilitate the transmission and desired
refraction of light. For example, the medium having the adjustable
refractive index n2 may be configured as a prism, as an optical
interface presented at an angle to the incident beam other than
perpendicular, as one or more optical windows through which light
may pass, as an open cell with optical windows and spacers in
between, or in any other suitable configuration. Further, the
switch 114 may also include other elements, treatments, or
characteristics to achieve desired characteristics. For example,
the interfaces 226, 228 between the various media may include an
optical coating, such as an antireflectance coating or an optical
impedance-matching material.
[0047] Referring to FIG. 3, an alternative exemplary embodiment of
the switch 114 comprises a first optical medium 310 having a first
refractive index n2. The first medium 310 is adjacent a second
optical medium 312 along the incoming light path and a third
optical medium 314 along the outgoing light path, each having a
particular refractive index n1 and n3. The various optical media
310, 312, 314 may comprise any suitable material, including solid,
liquid, gas, or plasma. In addition, the refractive indices of the
various materials 310, 312, 314 may be adjustable or substantially
constant, and may be selected according to any appropriate
criteria. For example, n1 and n3 may be approximately equal or
different.
[0048] Furthermore, any suitable number of light sources 110 and
light targets 112 may be used. Referring to FIG. 4, an alternative
optical switch module comprises a 2.times.1 switching module 400
including two light sources 410A-B and one light target 412. The
switch 114 comprises an adjustable switch element 414 having an
adjustable refractive index. When the switch element 414 is to
transmit light from the first light source 410A, the refractive
index of the switch element 414 may be selected to direct the light
toward the light target 412. Similarly, when the switch element 414
is to transmit light from the second light source 410B, the
refractive index of the switch element 414 may be adjusted to
direct the light at a more acute angle, thus transmitting light
from the second light source 410B toward the light target 412.
[0049] An optical switching module 100 according to various aspects
of the present invention may also be configured with multiple light
sources 110 and light targets 112. The optical switching module 100
may be configured with any suitable number of light sources 110 and
light targets 112, such as 2.times.2, 1.times.N, N.times.1, or a
three-dimensional N.times.M optical cross connection (OXC)
switching system. For example, referring to FIG. 5, a 2.times.2
switching module 500 has two light sources 510A-B and two light
targets 512A-B. The switch 114 suitably comprises a first switch
element 514 that receives light from the first light source 510A, a
second switch element 516 that receives light from the second light
source 510B, and a third switch element 518 and a fourth switch
element 520 that transmit incident light to the first and second
light targets 512A-B, respectively.
[0050] In a first state, the first switch element 514 is configured
to transmit light to the third switch element 518 and the second
switch element 516 is configured to transmit light to the fourth
switch element 520. Conversely, in a second state, the first switch
element 514 is configured to transmit light to the fourth switch
element 520 and the second switch element 516 is configured to
transmit light to the third switch element 518.
[0051] The refractive indexes of the first and second switch
elements 514, 516 and the relative positions of the switch elements
514, 516, 518, 520 are selected such that the light transmitted
through the first and second switch elements 514, 516 arrives at
the third and fourth switch elements 518, 520 at selected
angles.
[0052] The third and fourth switch elements 518, 520 are configured
to transmit light to the light targets 512A-B. The third and fourth
switch elements 518, 520 suitably have multiple states to transmit
light to the light targets 512A-B. For example, in a first state,
the third and fourth switch elements 518, 520 have appropriate
refractive indices to transmit light from the first switch element
514 to the first light target 512A and from the second switch
element 516 to the second light target 512B, respectively.
Conversely, in a second state, the third and fourth switch elements
518, 520 have appropriate refractive indices to transmit light from
the first switch element 514 to the second light target 512B and
from the second switch element 516 to the first light target 512A,
respectively.
[0053] Although the present embodiment relates to a 2.times.2
switch, any appropriate number of inputs and outputs may be
deployed, for example using different states for the various
switches. Referring again to FIG. 5, an additional switch element
522 may be included in the switching module 500 and accessed by
adding a third refractive state for the first and second switch
elements 514, 516 to target the additional switch element 522.
[0054] The switching module 100 may also be configured to transmit
light in three dimensions. Consequently, the light sources 110 and
light targets 112 may be situated in different approximate planes.
For example, referring to FIG. 6, a 3-D optical switching system
600 according to various aspects of the present invention includes
a switch 114 having a first switching element 610 and a second
switching element 612. The first switching element 610 is suitably
configured to transmit light at an angle to the incident beam in a
first x-y plane. The second switching element 612 is suitably
configured to transmit light at an angle outside the x-y plane.
Consequently, the light from the light source 110 may be
transmitted to the light target 112 when the light target 112 is
not in the same plane as the initial refraction of the light by the
first switching element 610.
[0055] An optical switching array may comprise multiple switches
114 operating in two or three planes. Referring to FIG. 7, an
exemplary M.times.N optical switching array 700 suitably comprises
an input array of switching elements 710 and an output array of
switching elements 712. Each of the individual switching elements
in the arrays 710, 712 may be individually controlled. In addition,
each array 710, 712 may have a different number of switching
elements, and each individual switching element may comprise one or
more switching modules and other components to direct light in a
particular direction.
[0056] Incident light from the light sources 110 is received by the
switching elements in the input array 710 and directed according to
the adjusted refractive index of the individual switching element.
The light is directed to a particular switching element in the
output array 712, which is adjusted to have a refractive index that
directs light to the appropriate light target 112. Each switching
element in the input array 710 may direct light toward one or more
switching elements in the output array 712; likewise, each
switching element in the output array 712 may receive light from
one or more switching elements in the input array 710.
[0057] The switch 114 may be configured in any appropriate manner
to facilitate the direction of light from the desired light source
110 to the desired light target 112. In various embodiments, the
switch 114 may comprise multiple components and/or materials. For
example, referring to FIG. 8, multiple switching elements may be
cascaded in a series to direct light at different angles. The
multiple switching elements may be aligned with parallel faces
(FIG. 8C), aligned with parallel backs (FIGS. 8A, 8D, and 8E), or
with an angled gap in between the two elements (FIGS. 8B and 8F) to
provide multiple refraction of the incident light beam. By
selecting the respective positions of the switching elements, the
propagation path of the light may be more effectively turned. Thus,
by forming a cascade of switching elements, the light may be
directed at selected angles according to a desired geometry.
[0058] Further, a cascade of switching elements may facilitate
directing light to a greater number of light targets 112. For
example, a first input switching element may selectively direct
light to a second and a third switching element. The second and
third switching elements may direct light to four different light
targets 112. Thus, light from a single light source 110 may be
directed to four different light targets. Any number of light
sources 110 and light targets 112 may be used by suitably
configuring the cascade of switching elements.
[0059] The optical switching module 100 may include additional
components to direct or collect light or otherwise affect the
performance of the optical switching module 100. For example, the
switch 114, light source 110, and/or light target 112 may include
one or more lenses, collimators, mirrors, or other elements.
Referring to FIG. 9A, an enhanced optical switch module 900
according to various aspects of the present invention includes a
light source 110 having a fiber optic light input 910 and a
collimator 912 for focusing light on a first switch element 914,
and a light target 112 having a fiber optic light output 930 and a
collimator 928 for focusing light received from a second switch
element 926.
[0060] At least one light path selectable by the switch 914 passes
through additional components to facilitate the focusing and
redirection of the light to the light target 112. In the present
embodiment, the optical path includes additional lenses, such as
two lenses 916, 918, which may be configured in any suitable
manner. Similarly, an output portion 920 of the enhanced optical
switch module 900 may include various elements for directing and
focusing light. In the present embodiment, the output portion 920
includes two lenses 922, 924 to focus and direct light to a second
switch element 926. The second switch element 926 directs the light
to the collimator 928, which focuses the light into an output optic
fiber, waveguide, or other port 930.
[0061] The lenses 916, 918 and 922, 924 suitably have common or
nearby focal points. Further, the lenses 916, 918 and 922, 924 may
comprise any suitable lenses and/or configuration of lenses. In the
present embodiment, the lenses 916, 918, 922, 924 comprise convex
lenses with different focal lengths. The focal length of the first
lens 916, 924 closest to the switch 914, 926 is suitably longer
than the focal length of the second lens 918, 922 farther from the
switching element 914. The components placed in the optical path
may, however, be configured in any suitable manner. For example,
the second convex lens 918 can be replaced by a concave lens (FIG.
9B). Additional elements may be added to the enhanced optical
switch module 900 independently or integrated into the other
components. Referring to FIG. 9C, a lens system may be used in
conjunction with switch elements comprising one or more movable
mirrors 932 to achieve the desired light propagation
characteristics. In addition, the mirrors 932 may be configured in
any suitable manner, such as flat, concave, or convex, to provide
any desired optical characteristics, such as to divert and/or focus
light at a desired location.
[0062] The switch 114 may be controlled by the actuator 116 in any
suitable manner, and the actuator 116 may be configured in any
suitable manner to cause the switch 114 to operate. The switch 114
may be configured to respond to a particular trigger event. The
actuator 116 is suitably configured to cause or restrain the event
and thus operate the switch 114. For example, the switch 114 may be
configured as a mechanical switch, and the actuator 116 may be
configured to cause the switch to change positions. Alternatively,
the switch 114 may be configured to have multiple refractive states
for selectively directing light in multiple directions, and the
states may be selected in response to any suitable trigger event,
such as application of heat, electric fields, magnetic fields,
light, or other stimulus.
[0063] The actuator 116 may be configured in any suitable manner to
control the event to which the switch 114 responds. For example,
referring to FIG. 10, an exemplary switch module 1000 comprises an
input switch element 1010 and two output switch elements 1012A-B.
The input switch element 1010 changes its refractive state in
response to a voltage applied to the material of the input switch
element 1010.
[0064] An electrical actuator 1014 is configured to provide and
terminate voltage applied to the input switch element 1010 to
control the switch 1000. The electrical actuator 1014 may be
configured in any suitable manner to apply the voltage to the input
switch element 1010. For example, referring to FIGS. 11A-B, the
electrical actuator 1014 may be configured as a pair of electrodes
1110 for applying a voltage across the input switch element 1010.
The voltage may be applied in any suitable manner, such as
perpendicular to the light path (FIG. 11A) or parallel to the light
path (FIG. 11B).
[0065] The electrodes 1110 may comprise added material attached to
the switch element, or may be integrated into other portions of the
switch 114 or actuator 116. For example, referring again to FIG. 3,
the optical media having the refractive indices n1 and n3 may also
comprise electrodes through which a voltage may be applied across
the variable refractive material. Similar configurations may be
used for switches 114 that respond to other electromagnetic events,
such as electric fields and magnetic fields. Similar configurations
may also be used for switches 114 that respond to thermal events,
for example by providing heating elements on the surface of and/or
embedded into the variable refractive material or the material
surrounding the variable refractive material.
[0066] Referring to FIGS. 12A-C, a light responsive switch module
1210 responds to the presence or absence of light, such as light of
a particular strength, frequency, or orientation. The light to
control the light responsive switch module 1210 may be applied in
any suitable manner. For example, control light for controlling the
switch 1210 may be provided by a control laser 1212. The control
light may be applied in any appropriate manner, such as parallel to
the path of the input signal light (FIG. 12A). The switch 1210 may
include a filter prior to or in the light target to filter the
light from the control laser 1212. Similarly, control light may be
applied along a path perpendicular to the path of the input signal
light (FIGS. 12B-C).
[0067] The actuator 116 may be added to or integrated into a
switching system comprising multiple switches 114, light sources
110, and/or light targets 112. The configuration of the actuator
116 may be selected according to the configuration of the switch
system and/or any other suitable criteria. For example, referring
to FIG. 13, an exemplary optical switch array 1300 according to
various aspects of the present invention comprises multiple light
sources 110 and light targets 112, such as those comprising fiber
optics 1310 and collimators 1312. The switch 114 comprises multiple
switch elements 1314 responsive to an event, such as electrical
voltages, currents, magnetic fields, and/or heat. The switch
elements may also be separated by a medium, such as glass. To apply
the signals to control the switch elements 1314, the actuator 116
suitably comprises multiple electrodes or thermal elements 1316
placed on either side of each switch element 1314. The electrodes
or thermal elements 1316 may then be controlled adjust the
refractive index of each switching element 1314.
[0068] In various alternative embodiments, the switch 114 and
actuator 116 may be configured to operate using optical tunneling.
Generally, optical tunneling facilitates the transmission or
reflection of light, or the transmission of light at certain
wavelengths and reflection of other wavelengths, by a barrier under
selected circumstances. Various materials, such as liquid crystal,
crystal, semiconductor, and/or organic materials, may be used to
enable and/or adjust the optical tunneling under certain
conditions, such as the application of heat, light, electric
fields, magnetic fields, and the like.
[0069] The switch 114 and the actuator 116 may operate in
conjunction with any appropriate type of optical tunneling. For
example, the switch may use total internal reflection (TIR).
Referring to FIG. 14, an exemplary switching module 1400 comprises
two external media 1412, such as prism-shaped media, having
substantially identical refractive indices, and an intermediate
medium 1414 having a variable refractive index between the external
media. The refractive index of the intermediate medium 1414 is
suitably lower that than that of the two external media 1412. Two
interfaces 1418, 1420 formed where the external media 1412 abut the
internal medium 1414 may be coated with antireflective
coatings.
[0070] In operation, light from the light source 110 arrives as two
beams from two input ports. The beams are incident on the first
interface 1418 and the second interface 1420 separately at
substantially identical angles. The angle of incidence is near the
critical internal reflection angle. When the refractive index of
the intermediate medium 1414 is decreased beyond a particular
threshold, each of the two incident beams is totally reflected by
the first and the second interfaces 1418, 1420. Alternatively, when
the refractive index of the intermediate medium 1414 is increased,
then the two incident beams are transmitted through the interfaces
1418, 1420 to opposite output ports.
[0071] Another exemplary form of an optical tunneling switch
employs multi-interferences. Referring again to FIG. 14, an optical
switch using multi-interferences may comprise the two external
media 1412, such as prism-shaped media, having substantially
identical refractive indices, and the intermediate medium 1414
having a variable refractive index between the external media.
[0072] Unlike the switch using TRI, the two interfaces 1418, 1420
are suitably coated with highly reflective coatings. The two input
optical beams are suitably incident on the first and second
interface 1418, 1420 at any angle which is smaller than the
internal reflection angle. When the wavelength of the input optical
signals is resonant with the cavity formed by the two interfaces,
the reflective coatings, and the refractive index of the
intermediate medium, the two interfaces reflect the input optical
signals separately. When the wavelength of the input optical
signals is not in the resonant state with the cavity, the two input
optical signals will be transmitted.
[0073] Accordingly, a switch using multi-interferences may operate
as a wavelength selective switch or a wavelength add/drop switch.
If one input port for the incoming signals has a multiple channels
on different wavelengths, and the other input port receives add-on
signals with multiple wavelengths, at the reflective state, the
incoming signals (for certain band of wavelength) are reflected to
an output port that is treated as the passing channel. While in the
transmission state, the incoming signals (for a certain wavelength)
are transmitted to another output port that is treated as the drop
channel. At the same time, however, the add-on signals with the
same wavelength are transmitted to the first output port that is
treated as the passing channel. Therefore, the add-on signals
(wavelength) are added into the normal transmitting (passing)
signals.
[0074] The optical tunneling may be controlled in any suitable
manner according to the variable reactive material. For example, in
FIG. 14, the variable refractive intermediate medium 1414 has a
refractive index that varies according to temperature, such as a
heat-responsive liquid crystal, organic or inorganic material,
semiconductor, or polymer. Thus, the actuator 116 suitably
comprises a heating or cooling system configured to selectively
provide or deprive the thermal conditions for optical tunneling. In
the present embodiment, the actuator 116 comprises an electric
heater 1416, such as an electrical resistance on each side of the
switch material 1414.
[0075] The heat-responsive tunneling switch module 1400 may be
configured in any suitable manner. For example, the light sources
110 and light targets 112 may comprise any appropriate components
and configurations. In the present embodiment, the light sources
110 and light targets 112 comprise fiber optics and collimators.
Alternatively, the light sources 110 and light targets 112 may
comprise optical waveguides 1710 (FIG. 17).
[0076] Further, the actuator 116 and switch 114 may be configured
according to the switch material used for variable refraction. For
example, referring to FIG. 15, a switch material 1510 may comprise
a liquid crystal material that is susceptible to variable
refraction according to a particular voltage across the switch
material 1510. The actuator 116 may comprise a pair of electrodes
1512 on either side of the switch material 1510 to provide the
appropriate voltage. Referring to FIG. 16, an alternative switch
material 1610 may be variably refractive upon exposure to light,
such as a particular frequency or orientation of light. A space may
be provided between the prisms 1412 to facilitate providing light
to the switching material 1610.
[0077] The optical tunneling switch systems may also be integrated
into units having multiple light sources 110 and/or multiple light
targets 112. For example, referring to FIG. 18, multiple switches
using optical tunneling may be adjoined to form a multiple-input
and multiple output optical switch system 1800 comprised of
multiple, individually operable switch modules.
[0078] In another alternative embodiment of an optical switch
system according to various aspects of the present invention, the
switch 114 comprises a mechanical switch to selectively transmit
light. The mechanical switch may comprise any appropriate switch
for selectively transmitting, blocking, filtering, and/or
reflecting light. For example, referring to FIG. 19A, a mechanical
switch 1900 according to various aspects of the present invention
comprises a first transparent substrate 1910 and a second
transparent substrate 1920. The substrates 1910, 1920 are
positioned parallel to each other. One or more materials 1912 are
suitably sandwiched between the substrates 1910, 1920 to cover
portions of the area of the substrates. For example, in the present
embodiment, one half of the area between the substrates is covered
by a reflective material such that the mechanical switch 1900 is
transparent on one side and reflective on the other. Alternatively,
the switch 1900 may include one or more filters (FIG. 19B), instead
of or in addition to the transparent area or the reflective
material, to transmit selected wavelengths and reflect others.
Further, the mechanical switch 1900 may be configured in any
suitable manner, for example as a rectangular, circular, or
cylindrical component (FIG. 19C).
[0079] The mechanical switch 1900 may be deployed in any suitable
manner to selectively transmit or reflect light from a light source
110. For example, referring to FIG. 20, the mechanical switch 1900
may be disposed between two light sources 2010 and two light
targets 2012. The mechanical switch 1900 may move in any direction,
such as laterally, vertically, or rotationally with respect to a
substrate. The actuator 116 moves the mechanical switch 1900. The
actuator 116 may comprise any suitable system for moving the
mechanical switch 1900, such as a magnetic coil, a pneumatic
actuator, a hydraulic actuator, or other appropriate system for
moving the mechanical switch 1900.
[0080] The switch system may be configured to selectively direct
light from the light source 110 to the light target 112. In the
present embodiment, the mechanical switch 1900 is deployed in a
2.times.2 switch configuration using a crossing pattern, though any
appropriate number of inputs and outputs may be used. When the
mechanical switch 1900 is in a first position, the transparent
portion of the mechanical switch 1900 is in the optical path, such
that light from the first light source 2010A is transmitted to the
second light target 2012B and light from the second light source
2010B is transmitted to the first light target 2012A. When the
mechanical switch 1900 is in a second position, the reflective
portion of the mechanical switch 1900 is in the optical path, such
that light from the first light source 2010A is transmitted to the
first light target 2012A and light from the second light source
2010B is transmitted to the second light target 2012B. The switch
1900 may operate in conjunction with any number of positions,
however, for example according to the number of different portions
of the switch 1900 having different transmissive or reflective
characteristics.
[0081] The mechanical switch 1900 may also be deployed in
conjunction with a biasing system. The biasing system suitably
biases the mechanical switch 1900 to maintain a selected position.
For example, the biasing system may be configured to bias the
mechanical switch 1900 into a particular position in the absence of
a signal, such as in the event of a power failure.
[0082] Referring to FIG. 21, an exemplary biasing system comprises
a frame 2110 attached to the mechanical switch 1900. The frame 2110
may be configured to engage a position retainer. For example, the
position retainer may comprise a spring-biased roller bearing (not
shown) that is biased towards the frame 2110. The frame suitably
includes a pair of notches 2112 for receiving the roller bearing.
When the mechanical switch 1900 is moved to a position, the roller
bearing engages one of the notches 2112, which tends to maintain
the position of the frame 2110 and the mechanical switch 1900 in a
position corresponding the current state of the switch.
[0083] An optical module 100 using multiple mechanical switches may
also be configured as an array to accommodate multiple signals. The
array may comprise any suitable configuration using multiple
switches to direct optical signals from the light sources 110 to
the light targets 112. For example, referring to FIG. 22, an
optical switch array 2210 according to various aspects of the
present invention comprises multiple mechanical switches, such as
mechanical switches 1900 as described in conjunction with FIGS.
19-21. The mechanical switches 1900 are disposed between light
sources 110 and light targets 112 to selectively direct light from
the light sources 110 and selected light targets 112. Each
mechanical switch 1900 may be operated individually to facilitate
switching for each light source 110 and light target 112. In the
present embodiment, the mechanical switches 1900 are configured in
a linear array on a substrate 2212. The optical switch array 2210
may be configured, however, in any suitable manner.
[0084] One or more optical switch modules and/or arrays according
to various aspects of the present invention may be deployed in one
or more components of a larger data or other communications system.
The communications system may comprise any suitable configuration
for managing and directing signals, such as an optic switching
module, an optic cross switching system, and/or a fast optical
switch for optical packet switching applications. Furthermore,
various systems may be combined to provide an optical packet cross
switching (OPXC) system.
[0085] A communications system for transferring data and/or
communications information may comprise a switching system for
directing signals to appropriate destinations. For example,
referring to FIG. 23, an optical switching system 2300 according to
various aspects of the present invention suitably comprises a
multiplexing system 2310, an optical cross connect (OXC) switching
system 2312, a multichannel monitoring (MCM) system 2314, a
variable optical attenuator (VAO) 2316, and a central control
system 2318. The optical switching system 2300 may use any
appropriate protocols and techniques for transferring information,
such as time division multiplexing or dense wavelength division
multiplexing.
[0086] The multiplexing system 2310 facilitates separation and
recombination of signals and transfer of individual signals from
the light source 110 to the OXC switching system 2312, and from the
OXC switching system 2312 to the light target 112. In the present
embodiment, the multiplexing system 2310 demultiplexes an incoming
signal having multiple components on one or more inputs. For
example, the incoming signal may comprise a multiplexed signal
having multiple channels, such as channels using different
wavelengths. The demultiplexing portion of the multiplexing system
2310 suitably separates the incoming signal into the separate
channels for transmission to the OXC switching system 2312.
Similarly, the multiplexing system 2310 may multiplex the outgoing
channels to combine multiple outgoing signals for transfer on a
single fiber or other connection.
[0087] The multiplexing system 2310 may also include an optical
add/drop multiplexing (OADM) system having an optical add module
2320 and an optical drop module 2322. The OADM system facilitates
addition of signals for transmission and/or diverting of signals to
a different light target 112. In the present embodiment, the OADM
system may accommodate electrical as well as optical signals, such
that electrical signals may be converted to optical signals for
transmission to light targets, or optical signals, such as drop off
signals, may be converted to electrical signals for compatibility
with an electrical system.
[0088] The multiplexing system 2310 may be implemented in any
suitable manner. For example, the demultiplexers and/or the optical
add module 2320 may include multiple optical switch modules and
arrays according to various aspects of the present invention, such
as a cascade of 1.times.2 switches like those described in
conjunction with FIG. 2, configured to split a combined signal into
individual components. Correspondingly, the multiplexers and/or the
optical drop module 2322 may comprise a cascade of 2.times.1
switches, such as the switches described in conjunction with FIG.
4, to combine individual channels into one or more signals.
[0089] The OXC switching system 2312 provides for the transfer of
signals from one channel or connection to another. The OXC
switching system 2312 may be configured for any appropriate
applications, including fiber management and distribution, resource
sharing, monitoring, disaster recovery and restoration, fiber or
copper testing, and/or dynamic network management. The OXC
switching system 2312 may be implemented in any suitable
configuration to transfer signals. In the present embodiment, the
OXC switching system 2312 comprises a switching array having
multiple optical switches, such as the refractive switches and/or
mechanical switches described above. For example, the OXC switching
system 2312 may comprise a 3-D switching array, such as the 3-D
switching array 700.
[0090] The MCM system 2314 and VOA 2316 are suitably connected to
the OXC to monitor and optimize signals transferred from the OXC
switching system 2312 to the multiplexing system 2310. The MCM
system 2314 may be implemented in any suitable configuration, such
as one or more N.times.1 optical switch modules having signal
detectors, for example an optical switch system 400 as described in
FIG. 4 and having light target 412 including a signal detector. The
N.times.1 optical switch may comprise, however, any suitable
optical switching module. Referring to FIG. 24, in the present
embodiment, the N.times.1 optical switch 2410 includes an input
port 2412 and an output port 2414. The input port 2412 suitably has
one or more input channels, each of which is suitably collimated.
The output port 2414 has at least one output channel having an
aperture. Light from the aperture is provided to a signal detector
2416 for analysis of the signal. For example, the light from the
aperture may be provided as a feedback signal to the central
control system 2318 for analysis.
[0091] The MCM system 2314 may also comprise an optical testing
system and a signal processing system. The optical testing system
is also configured to test various signal characteristics, such as
the optical signal intensity, wavelength, and polarization of
signals handled by the OXC switching system, using the signal
processing system. The optical testing system may then provide
information to the central control system, such as via the feedback
system, to adjust the signal characteristics into desired ranges or
to desired targets.
[0092] The VOA 2316 may provide any appropriate function for
adjusting signals in the optical switching system 2300, such as
flattening the output of the OXC switching system 2312, balancing
signal levels, and protecting receivers against overloads. In the
present embodiment, the VOA 2316 is integrated into the OXC
switching system 2312, and may operate in conjunction with the
feedback signals from the MCM system 2314. In the present
embodiment, the VOA 2316 comprises a multi-channel optical variable
attenuation (MCOVA) system having multiple channels to address
multiple signals simultaneously. The VOA 2316 suitably also
responds to signals from the central control system 2318.
[0093] In the present embodiment, the VOA 2316 may be integrated
into the OXC switching system 2312. For example, if the MCM system
2314 indicates that an optical signal is too intense, the MCM
system 2314 and/or the central control system 2318 may signal the
VOA 2316 to reduce the intensity of the signal. In the present
embodiment, the VOA 2316 may reduce the intensity of the signal by
adjusting the refractive index of the corresponding switch module.
By adjusting the refractive index, the direction of the optical
beam may be slightly misaligned with the receiving port, which
tends to reduce the intensity of the resulting optical signal.
[0094] The central control system 2318 provides the control
function for the various components of the optical switching system
2300, such as the OADM system 2310, the OXC switching system 2312,
the MCM system 2314, and the VOA 2316. The central control system
2318 may comprise any suitable control system, such as a
conventional computer system configured for managing switch
traffic. The central control system 2318 may also be connected to a
network management system for integration into another
communications system. In the present embodiment, the central
control system 2318 receives signals from the MCM system 2314 and
adjusts various output signals accordingly. For example, the
central control system may provide signals to the VOA 2316 to alter
signal intensity or other characteristic.
[0095] The communications system may also be configured to
accommodate optical packet switching, such as optical packet
add/drop switching. Packet signals suitably comprise signals having
a header and a payload. The header describes characteristics of the
packet signal, and the payload comprises the data for the
signal.
[0096] To accommodate packet signals, the communications system may
utilize fast switches for adding, passing, and dropping packets.
The switches may be configured in any suitable manner, including a
multiple switches in parallel, in a cascade, or in any other
configuration. For example, referring to FIG. 25A, an optical
packet switch module 2500 suitably comprises a switch 2510 having
two inputs for input optical signals and additional optical packet
signals. The switch 2510 also has two outputs, one for passsing
optical packet signals and the other for dropping optical packet
signals. The switch 2510 may be configured, however, to have any
suitable number of inputs and outputs. The switch 2510 suitably
comprises a fast switch for switching signals, for example
according to information in the header portion of the packet. For
example, in the present embodiment, the switch 2510 comprises a
switch having a single switching signal for controlling the
switching, such as a 2.times.2 switch using a crossing pattern like
those described in conjunction with FIGS. 14-18, 20, and 22.
[0097] The optical packet switch module 2500 may also include a
control system for controlling the switching function, for example
in conjunction with information in the packet signal. For example,
referring to FIG. 25B, a system control unit 2512 receives signals
from the input optical signal and the additional optical input
signal, for example through beam splitters, and may receive signals
from the pass signal output and the drop signal output as well.
Based on the information in the various signals, the system control
unit 2512 may operate the switch 2510 to direct the signals. In
addition, the optical switching system may include optical delay
lines 2514 in the optical path, and/or the system control unit 2512
may provide a data buffer and/or a delaying function to facilitate
proper switching. For example, the system control unit 2512 may
include optical-to-electrical signal conversion and
electrical-to-optical signal conversion to facilitate delays for
effective packet switching and/or to provide compatibility with
electrical systems.
[0098] A packet switching system may be configured to handle packet
signals, for example using the various optical switches and the
packet switching systems. The communications system may be
configured in any appropriate configuration for handling packet
traffic. For example, referring to FIG. 26, an optical packet
communications system 2600 according to various aspects of the
present invention comprises an optical packet cross connection
(OPXC) communications system including an optical packet switch
2610. The OPXC communications system 2600 also suitably includes
other components for facilitating operations such as the
multiplexing system 2310, the optical cross connect (OXC) switching
system 2312, the multichannel monitoring (MCM) system 2314, the
variable optical attenuator (VAO) 2316, and the central control
system 2318. The OPXC communications system 2600 may use any
appropriate protocols and techniques for transferring information,
such as time division multiplexing or dense wavelength division
multiplexing.
[0099] The optical packet switch 2610 receives input signals, such
as from the demultiplexing system 2310, and directs the incoming
signals according to, at least in part, information in the packet.
The optical packet switch 2610 may be configured in any suitable
manner, for example comprising an array of optical packet switch
modules 2500. The optical packet switch 2610 may also operate in
conjunction with a conversion system for altering signals for
effective handling. For example, the present optical packet
communications system 2600 includes a wavelength converter 2612 to
facilitate changing the wavelength of a signal. The wavelength
converter 2612 may be used by the optical packet communications
system 2600 to change the wavelength of a particular signal so that
it may be used in a different channel. Thus, if a particular
channel (corresponding to a particular wavelength) is overburdened,
the optical packet communications system 2600 may change the
wavelength of the signal for transmission via a different
channel.
[0100] The multiplexing system 2310 also suitably includes a
wavelength tunable optical add module 2614. The wavelength tunable
optical add module 2614 facilitates addition of signals for
transmission. The wavelength tunable optical add module 2614 may
accommodate electrical signals, which may be converted into optical
signals having a particular wavelength for transmission on a
selected channel. The wavelength tunable optical add module 2614
may also convert the added signal into a packet.
[0101] Similarly, the multiplexing system 2310 also suitably
includes a wavelength tunable optical drop module 2616. The
wavelength combining optical drop module 2616 facilitates dropping
of signals for transmission to another system. The wavelength
combining optical drop module 2616 may accommodate electrical
signals, which may be converted from optical signals having a
particular wavelength for transmission as electrical signals. The
wavelength combining optical drop module 2616 may also convert the
added signal into or from a packet.
[0102] The optical packet communications system 2600 may also
include any other appropriate components. For example, various
subsystems, such as the multiplexing system 2310, the optical cross
connect (OXC) switching system 2312, the multichannel monitoring
(MCM) system 2314, the variable optical attenuator (VAO) 2316, the
wavelength converter 2612, the wavelength tunable optical add
module 2614, the wavelength combining optical drop module 2616, and
the optical packet switch 2610, may have dedicated control units.
For example, the control units may comprise distributed control
units connected with the central control system 2318 to offload
tasks from the central control system 2318. In addition, the
central control system 2318 may be configured to communicate with
the network management system through the optical packet switch
2610.
[0103] The particular implementations shown and described are
illustrative of the invention and its best mode and are not
intended to otherwise limit the scope of the present invention in
any way. Indeed, for the sake of brevity, conventional
manufacturing, connection, preparation, and other functional
aspects of the system may not be described in detail. Furthermore,
the connecting lines shown in the various figures are intended to
represent exemplary functional relationships and/or physical
couplings between the various elements. Many alternative or
additional functional relationships or physical connections may be
present in a practical system.
[0104] The present invention has been described above with
reference to a preferred embodiment. However, changes and
modifications may be made to the preferred embodiment without
departing from the scope of the present invention. These and other
changes or modifications are intended to be included within the
scope of the present invention.
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